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jpearson311 07-19-2013 01:07 PM

'71 Volvo rough idle
Hi all. I have a '71 Volvo 1800 that has a strange idling problem. When I first start it up, it idles fine, but then all of a sudden, around 30 seconds or so into idling, it drops down significantly. It's a 4 cylinder engine and 2 of the spark plugs have white tips, but all of the injectors are "squirting" appropriately. Does anyone have any idea why this might be happening? Thanks!


ukrkoz 07-21-2013 06:52 PM

Go here:
Scroll down to color chart, find your plugs, and read what it means.
Wanted to say - you run lean on those 2 plugs, ha-ha, indeed:
A clean, white insulator firing tip and/or excessive electrode erosion indicates this spark plug condition. k This is often caused by over advanced ignition, timing, poor engine cooling system efficiency (scale, stoppages, low level), a very lean air/fuel mixture, or a leaking intake manifold. When these conditions prevail, even a plug of the correct heat range will overheat.
Clean fuel injectors.

msmith5554 08-21-2013 08:17 PM

Sounds like you have a vacuum leak. With the engine idling, spray mist of water around the engine area. The engine will start to die or run rough if the leaking area gets sprayed

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